A DC-to-DC converter is a type of power converter that converts a source of direct current (DC) from one voltage level to another. DC converters are utilized in portable electronic devices, such as cellular phones and laptop computers, because these are supplied with power primarily from batteries. In addition, such devices may contain several sub-circuits, each requiring a different voltage level from that supplied by the battery or an external supply. Further, the battery voltage declines over time upon draining of its stored power. Most DC to DC converters also regulate the output voltage.